'use strict';

function get_union(collection_a, collection_b) {
  //在这里写入代码
  for (var i = 0; i < collection_b.length; i++) {
    if (collection_a.indexOf(collection_b[i]) === -1) {
      collection_a.push(collection_b[i]);
    }
  }
  return collection_a;
}

module.exports = get_union;

